Apparatus for purifying metallic mercury



April 27, 1948. H, ALLEY Er AL 2,440,456

APPARATUS FOR PURIFYING METALLIC MERCURY Filed Dec. 9, 1942 fizz/eldersfla 'oldiflAllfii Begywrggz Ef'ree 9' PatentedApr. 27, 1948 v UNITEDSTATES PATENT OFFICE APPARATUS FOR PURIFYING METALLIC MERCURY Harold R.Alley, Northbrook, and Benjamin F. i

Frceberg, Chicago, Ill.

Application December 9, 1942, Serial No. 468,395

1 (Jlaim. (Cl. 266 34) The invention relates to the purification ofmercuryand has for its general aim' the provision of a new and improvedapparatus for purifying metallic mercury that has become contaminated.

Other objects and advantages will become apparent in the followingdescription and from the accompanying drawings in which the figure is adisclosed, but intend to cover all modifications and alternativeconstructions falling within the spirit and scope of the invention asexpressed in the appended claim.

Since the present invention has wide spread utility in the purificationof mercury that has become contaminated while in industrial use, it willbe considered primarily in this connection.

Mercury in such industrial uses as in mercuryarc rectiilers, manometers,electrical contacts and the like, becomes increasingly inemcient inperforming its intended function as it becomes contaminated, yet theaflinity for mercury of many contaminants of widely differentcharacteristics makes it extremely difilcult, if not impossible, tomaintain the mercury in a pure, emcient condition. It is thereforenecessary that the mercury be purified from time to time to restore itsefliciencyr Contaminated mercury is dimcult to purify as will beunderstood when it is considered that the contaminants commonlyencountered may include such extraneous material as copper, iron, floordirt, grease, oil, solder, water, and mercury oxides. Moreover, suchcontaminants may be present as a coating or film, as an amalgam or as amaterial in solution in the mercury.

According to the present process a body of contaminated mercury to bepurified is subjected to a series of purification steps, each of whichis effective to remove most, if not all of'c'ertaln classes ofimpurities or contaminants, and which steps generally condition theimpure mercury for duced to a state of substantially colloidal finenessto insure rapid and complete removal of the acid .and water solublematerials. Thus, the mercury passes to the first of two washing deviceswhich are preferably connected in series. In the first or upper washingdevice, indicated at I I2, the

mercury is given an acid wash preferably with. dilute (on the order of10%) nitric acid. The J washer comprises a suitable container I2 intothe upper portion of which the mercury iszintIO- duced in a fine streamthru a restricted orifice li A mechanical stirrer I3 within thecontainer li 'is arranged to be driven at'a high rate of speed by amotor M. This high speed action on the incoming fine stream of mercurybreaks'it into extremely fine particles substantially, if not actuallyof colloidal fineness. The stirrer [3 also causes the mercury particlesto travel through a long spiral path downwardly toward a collectionpoint at the bottom of the container. m At the collection point theparticles recombine into one mass.

The mechanical beating action of the stirrer it tends to break up anyamalgams in the mercury body and the fineness of the particles as Wellas the long path through which they travel as zinc, tin, lead, andcopper from the mercury.

the more eiiicient treatment thereof in a subse- The conversion of.these mercury soluble metals into their salts is, of course,accompanied to some extent by the similar conversion of mercury, but themercury thus lost may be. recovered in a subsequent step in the process.

Preferably the acid wash container l2 has a bottom outlet communicatingwith a conduit I5 having a. return bend providing a trap for maintaininga small quantity of mercury I2 in the bottom of the container.The-conduit leads to the second or water washing device It, and isarranged to discharge a fine stream of mercury thereinto through a'nozzle Il The watnwashing device is generally like the first and also includes a motor driven stirrer I! for again breaking the fine stream ofmercury into extremely small particlesin a bath of wash water whichpreferab'y flows continuously through the con-.

tainer ll from a bottom intake pipe i8 to a top outlet pipe l9. The fineparticles of mercury are adequately washed as they travel to the bottomof the container l1, thus removing water soluble metal salts and tracesof acid from the mercury.

The mercury after the water wash is .withdrawn from the container l1through a bottom The bottom outlets may be valve controlled, as at 22,to permit the liquids th'erein to be withdrawn as desired. Inthe case ofthe acid wash device this is used to remove the spent acid. The acidcontainer I! may have a top outlet 23 for connection with an exhaustpump to withdraw acid fumes. In the water container I'I' the bottomwater inlet l8 and a top outlet l8 produce a continuous flow or water,and in this, connection it will be noted that the outlet is far from thestirrer to minimize the loss 01- merw y with the water stream.

The stirring members, in this instance, comprise motor driven rods 24having radially pro- ,Iecting stems 20. The members are of stainlesssteel or other suitable material which is acid and water resistant, andhas no amnity for mercury. The motors are adapted to drive the stirrersat high rates or speed. It is preferred that the driving motors bearranged for variable control, since the proper operating rate. may varywidely, as for example between 2400 R. P. M. and 4000 R. P, M. dependingon the purity of the mercury, the strength of the acid wash, the rate ofmercury flow, and the desired fineness oi the particles.

We claim as our invention: a

A washing device for use in the purifying oi mercury comprising. incombination, an acid wash container adapted to contain a body of acidwash and having a mercury collection space at the bottom and a mercuryoutlet opening from said space, a vertical rotary stirrer projectingtain water wash and having a mercury collection space at the bottom anda mercury outlet opening fr )m said last mentioned space, a verticalrotary stirrer projecting into the top of said water wash container andlocated above said last mentioned collection space, a conduit connectedto said first mercury outlet and projecting into the top of said waterwash container and having a. discharge orifice for delivering a streamof mlnute the stream of mercury directed thereto and to cause thedispersed particles of mercury Number into th'etop of said container andbeing located to move downwardly through a spiral path to the associatedcollection space.

HAROLD R. ALLEY. BENJAIWIN F. FREEBERG.

REFERENCES CITED The following references are of record in the file ofthis. patent:

. UNITED STATES PATENTS Name I ,Date 659,485 Maigner Oct. 9, 19001,718,103 Baxter June 18, 1929 2,032,602 Stearns Mar. 3, 1936 2,275,266Meyer Mar. 3, 1942 OTHER REFERENCES Quantitative Analysis byElectrolysis, Cassen and Hall, pages 127 and 128,

The Industrial Chemist, July 1929, pages 289- 292, and Feb. 1932, pages63 and 64.

